Deep insulating trench

Abstract

Deep isolation trenches having sides and a bottom are formed in a semiconductor substrate. The sides and the bottom are coated with an electrically insulating material that delimits an empty cavity, and forms a plug to close the cavity. The sides of the trench are configured with a neck that determines the depth of the plug, and a first portion that tapers outwards from the neck as the distance from the bottom increases. Deep isolation trenches may be applied, in particular, to bipole and BiCMOS circuits.

Description

[0001]This application is a 371 of PCT / FR02 / 02029 Jun. 13, 2002.FIELD OF THE INVENTION[0002]The present invention relates to the manufacture of integrated circuits, and more particularly, to circuits using bipole or BiCMOS technologies.BACKGROUND OF THE INVENTION[0003]Deep isolating trenches formed in a substrate are intended to isolate the different elements of the circuit from each other, and to minimize parasitic components that exist between the structures. These deep isolating trenches are known as DTI (Deep Trench Isolation). Deep means that the depth of the trenches is greater than their width, and is much greater than the depth of the buried layers in the substrate. These deep trenches are used to separate the N+ and P+ buried layers, and thus reduce the perimeter component of the collector / substrate capacitance. These capacitances contribute to the calculation of circuit noise and to the oscillation frequency of bipole transistors.[0004]Deep isolating trenches surround bipo...

AI Technical Summary

Benefits of technology

[0010]In view of the foregoing background, an object of the present invention is to provide a different system in which the isolating capacity of a deep isolating trench is minimized, and without introducing any risk of dislocation of the substrate.

[0013]The risks of dislocation in the substrate are low, due to the presence of the empty cavity and the small volume of the electrically insulating material that only coats the sides and the bottom of the deep trench. The layer of electrically insulating material that delimits the empty cavity has a relative elasticity, which a solid block does not have.

Problems solved by technology

The risks of dislocation in the substrate are low, due to the presence of the empty cavity and the small volume of the electrically insulating material that only coats the sides and the bottom of the deep trench.

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